Where the sharpness comes from: A tour of Sigma's factory

Some people are happy to shoot with lenses and think only of the results, but it can also be fascinating to think about how such complex, precision pieces of engineering are made. Some insight is provided by Dave Etchells over at Imaging Resource, who has just posted a story about his visit to Sigma's factory in Aizu, Japan. Etchells follows the process from shaping the lens surfaces, to polishing, assembly and testing.

However, no matter how hard you try, you can't make every lens perfect - as Lensrentals Roger Cicala explains in his recent blog post. He looks at lens production from the perspective of manufacturability and engineering tolerances, and what's done to mitigate against the unavoidable inconsistencies they bring.

Comments

Kudos to DPReview for collaborating with other industry insiders and linking to such a great read.

I spent most of my life in hi tech machining environment and I'm astonished to see such informative and easy to understand story about complexity of processes required to build world class optics. It is also a tribute to a "human factor" so often forgotten in similar articles. Dave's inside look at how serious and committed to perfection Sigma is (testing section) is priceless.Thank you Dave.

I was surprised to see how aged their equipment is; by the look it is probably from the 80's. No wonder they have to test every lens. Still koodos to Sigma for producing some nice lenses on such dated equipment.

I am not sure what your experience is. I inspect lots of factories and this Sigma factory would be one of the most modern factories I have ever seen!

Please also do not confuse wear and tear with age.

Last but not least, it is not relevant how old a machine is, rather how it is maintained and calibrated. And by the looks of it Sigma factory management is very organized and structured, thus they would have a great maintenance program.

It really is fairly up to date. The control on that Mitsui Seiki indicate it's probably only 20 years old at the most (it looks like it's a late 90s early 00, I can't tell for sure from the picture). And the Mitsubishi EDMs, less than 10 years old (actually probably more like 5 due to how new that control is).

You might be surprised, but even modern large jumbo jet aircraft are running on landing gears milled out by 30+ year old machines.

Nonsense. Every manufacturer has to test every product (lenses or not) if they want to assure top notch quality and tolerances. The equipment is not old at all. And even old equipment, when maintained properly and calibrated can produce excellent and consistent products. This factory looks not only clean but very well maintained as well.

Finally, the obvious quality of the products speaks for itself. Sigma produces some of the very best lenses ever tested!

Sure. The machines may appear old, and maybe they are. What matters is the interface tooling, (which makes the cuts). I'm sure Sigma, like most large firms, have a staff of skilled tool and die makers whom maintain them. What's missing in many of the shots are those very same workers, whom most likely didn't want to be photographed and stepped away, (one less model release to be signed).

Machine tool manufacturers produce in low volume and so re-use as much as they can from one generation to the next. The business end of things, the software controllers and actual tooling are where development takes place, while things like the outer casing and attachment points might be the same as it was 25 years ago because there's no need to spend an engineer's time on that.

If all lenses today are made on $500,000 computer-controlled machines, how come some lenses are better than others? Does it come down to design and glass materials only, or are there still variations in polish and accuracy of curvature of the elements?

The list of variations is quite long actually: * Choice of Materials* Choice of tools (the bits you put into the CNC)* Your original design (CAD)* Your program to turn your CAD into a part (CAM)* Maintenance of the machine* How intelligent you adjust for deviations, such as change of temperature* How accurate you measure machined parts and then compensate your CAM* Integration of your assembly process* How your original design considers assembly tolerances* Final quality control of assembled product and feedback to assembly process

Above list is just a very rough overview. Great initial design considering all kinds of tolerances as well as measuring your results with feedback to production in many places as well as monitoring that all these processes are carried out properly, as well as a continuous improvement that goes through all steps of productions and layers of design and management are all very crucial.

it's interesting that Canon have the most automated production lines and others rely more on human (Chinese, Thai) but the results are not very different.

especially I think EF24-70/2.8L2 was designed from very beginning for efficient manufacturing but qualities are distributed over similar scale though the average is higher than all rivals.

maybe it's more for lower cost than higher quality and we as users don't enjoy the former yet. the previous EF24-70/2.8L used to be sold at just a grand, USD 1,039 (new with warranty) that I can remember, and they were hand-tuned (as well as "German" lenses made by Sigma).

These water leaks have been vastly blown out of proportion. The Japan Nuclear Regulation Authority has released measurements of the radioactivity in sea water sampled in the sea off Fukushima, Miyagi and Ibaraki. In all cases the measurements are either very very low or beneath the limit of detection. On this evidence, it is hard to see a risk to anything. The crisis is mostly one of perception than one of reality.

Yeah...very nice, but still I don't understand why two Sigma lenses I had (100-300/4EX and 10-20/3.5-5.6) were rubbish. Both were extremely out of focus, actually only one side of the image was out of focus...

Etchell's tour and write-up of the Sigma factory is excellent. I'm very impressed with my Sigma lens and after seeing the complex and time consuming manufacturing process I'm surprised Sigma lenses don't cost more, a lot more.

Well, Japanese business model is to produce high quality at high volume. The country has no natural resource. Their only resource is the people and their skills. If they charge too much for their product like the Germans do, fewer people can afford and fewer Japanese can find employment.

It is no different from an Apple product, or any electronics product.

But I am afraid their cost will increase if they can't find a renewable energy source to replace nuclear though.

The number of non qualified and erroneous comments on this site are almost never ending.

The contamination control procedures at Sigma look anything but disciplined or professional, instead appearing to be run by amateur managers pretending to have been formally trained in the field, faking it.

The staff in cleanroom "bunny" suits more for visual effect to impress the unknowing, as the staff at Sigma are improperly gown (female in coating lab, female using interferometer, female inspecting lens, two men standing next to possible ESD station) with individuals not wearing gloves, sleeves not properly pulled down exposing skin surface and very high particle shedding surface.

Seeing the cleanroom procedures being as they are suspect the lab's ESD procedures require scrutiny as well.

I would then immediately review and shut down all lab operations, remove the process engineer and lab managers, produce new training material and retrain the cleanroom staff, all prior to restarting lab operations.

My qualifications, I wrote many of the ESD, and cleanroom procedures for ISO 3-8 (FED STD 209E 1-100,000) at the Laser and Sensor Products Center at Northrop Grumman as the Process Engineering Manager, and Member of the Technical Staff, today the de facto base document for the entire Aerospace Systems sector.

expect lower prices for Japanese have been devaluating yen (lost near 30% in one year), are going to raise consumption tax for lower corporation tax, and make it easier for companies to fire employees ...

groucher, most (not all but most) of Nikon's 20 year old's BEST prime glass is soundly beaten to a pulp, flattened, chopped into small boxes by some of the newer lens designs.Disclaimer: I have loads of the old Nikkor classics & love them nonetheless, including the (unbeaten IMO) Noct.

... and thinking of DPR's future, how come I find more and more sources of good digital photography elsewhere compared to 8 years ago? A lens rental site disclosing the quality assurance process they run on their lens stock makes for a better read than found on this site here for quite some time!Diversity isn't the only key to survival, Simon. Remember where this site came from...so hats off for the courage to actually link to the good stuff over at IR and Lens Rental. A good service to your web site visitors (= customers)!

In that context: Thanks for NOT linking to rumor sites, that "service" is taken care of by forum rumor mongers to an over-saturating degree :-(

After watching the tour of the factory and knowing about the processes and precision that they (and others too) need to abide by, I kind of wonder why a 16 element 2.8 ED etc piece of optical precision glass can cost 400$ and a pair of Gucci or Rayban sunglasses with a SINGLE piece of UV-protected plastic can cost the same?

Great inside what really goes into a lens cost. Yes, it is- expensive optical glass ~proportionally to its weight- polishing of the sufrace - proportionally to surface areas of the lenses - coating - ~proportionally to surface areas of the lenses- assembly - ~proportionally to number of elements

peevee1 - you forgot about one thing: Higher precision = higher price.So if you want really high quality lens that's small at the same time (for example - because it's used on a small size sensor like m4/3) than it's price will be higher.That's why all these 50s are cheaper on DSLRs than CSCs - noone cares much about small size and the sensor is large, so you can allow yourself some more... freedom in manufacturing in order to pull the price down.

"Smaller, lighter lenses are also cheaper to make - don't fool yourself thinking otherwise."I am afraid it is not that simple. Smaller lenses for smaller sensors require higher tolerances and precision just because the elements that move when focusing/zooming have a much shorter range. Usually, shrinking an object by ten needs the absolute tolerance to be divided by ten. If you manufacture a lens with a 1 micron tolerance, then a lens ten times smaller would require a 0.1 micron tolerance at least.

I want to believe ... but the fact is no one is abandoning their Canikony lense in any class to use the Sigma. Unless they're a shill like I've seen in the Canadian photo press.

Nothing against Sigma but your past history follows you around. It's just not a simple case of throwing your shittty underwear in the wash with a sheet of Bounce and think you'll come out smelling like .... mountain meadow.

You are living way in the past. Sigma in no way resembles the company it once was, and that has been the case for many years now.

Just look at the build quality of Sigma's cameras, for example. They are top notch and as good as anything out there. Then consider the truly revolutionary picture quality their cameras are capable of. They are the only camera maker that has done anything truly significant to increase image quality.

Finally, is it really necessary to use disgusting toilet metaphors to make your point?

"past history follows you around"....I think Sigma right now is an excellent example of how a company can turn around from a bad reputation by doing an exceptional job. They're not just making lower quality, cheaper versions of common lenses anymore. Recently, they've put out:-18-35/1.8: no other manufacturer has a f/1.8 zoom-35/1.4: as good as (or better than) first party versions for a lower price-USB dock: adjust lenses without having to ship them offAnd that adds to their already strong portfolio with lenses like the 120-300/2.8 (no one else has a 300/2.8 that zooms back)In terms of lenses, Sigma right now is on track to beating first party manufacturers at their own game. If they continue to play it right, Sigma could come out smelling like mountain meadow.

Well, I don't know - all Tamron lenses I got are there only because Sigma has even worse products.There are right now only 4 outstanding lenses from Sigma. They're still long way from beating crap out of Tamron. And most likely - till than Tamron will catch up and beat them again.

Though definitely - Sigma knows where's a warm spot in Photographers soul and right now - that's where they're aiming. With a great success as you can see from chlamchowder's post.

In my days of engineering and working with molding, extrusion and tooling of materials, even though it was Medical devices, I can relate to much of the article. A hand made prototype could prove a great design. Then came the real hard part: repeatability in an automated process. Which involved a different team of engineers and technicians skilled in the art.

Hopefully this article sheds some light on why a good Quality Assurance department can make the difference in a respected product. That if you do get a lemon, just exchange it for another. It happens.

I think that applies to all manufacturing, i worked for nine years in commercial printing,We made carton boxes of all shapes and sizes for companies, from boxes for fake limbs down to small candy boxes, cereal boxes and so on, many designs look good on paper but the machinery cant handle everything.issues that can come up are "width of the box vs height" to long and narrow it wont go through properly (we did a ton of DIY to fix so many issues),the thickness of the carton (to thin it would rip, to thick it would refuse to go through)The color used (if it was to wet or the wrong color used it would smudge all over and be ruined),what kind of coating is on the carton? (if the coating was not good enough we had to use another type of glue)

And so many things could go wrong because of the designs and so many did, we however rarely had to turn down a job.

I agree. A few times we had to go back and redesign or deal with material change issues in the original design that would help facilitate mass production. With medical devices, there was a zero tolerance for any failure, (for obvious reasons). So changes were not based on making it cheaper, but making it safer to mass produce and thus reduce error rates.

It was tedious work, with design cycles up to five years. Company employees whom were hospitalized would request that doctors use our products because they knew how safe they were. That's real pride.

I own two of them, the DP 1 and 2 Merrill series cameras. No matter how many pictures I take I am truly stunned every time I develop a raw image from them. No other camera and lens has done that for me. Staggering picture detail and quality. They just need to make the Foveon sensors more sensitive to improve high ISO performance.

Yep, the best of Sigma, Tokina and Tamron lenses are as well built as anything out there. The best built and finished lens I ever owned was a Tokina ATX lens. It was also the sharpest.

All major camera and lens manufacturers make lenses of varying quality, both in build and image quality. The cheapest built lenses I have owned were Canon. The cheapest of the Nikons look no different.

Good info and glad they didn't stick you with the dinner bill. The part about them rejecting a lot of lenses that don't quite measure up was very interesting because with so much automation, I'm sure it's tempting to give everything a pass.

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